case BatchJobExpireDeleted:
		if len(ef.Tags) > 0 || len(ef.Metadata) > 0 {
			return BatchJobYamlErr{
				line: ef.line,
				col:  ef.col,
				msg:  "delete type filter can't have tags or metadata",
			}
		}
	default:
		return BatchJobYamlErr{
			line: ef.line,
			col:  ef.col,
			msg:  "invalid batch-expire type",
		}
	}

	for _, tag := range ef.Tags {
		if err := tag.Validate(); err != nil {

	// Helper function to register a collector and return a gatherer for it.
	mustRegister := func(c ...prometheus.Collector) prometheus.Gatherer {
		subRegistry := prometheus.NewRegistry()
		for _, col := range c {
			subRegistry.MustRegister(col)
		}
		r.MustRegister(subRegistry)
		return subRegistry
	}

	// Register all collectors and create gatherers for them.